Analog gun (selection of consumable cartridge materials)

ABSTRACT

Apparatus for testing the potential of polymeric materials for use in the manufacture of cartridges and the like is disclosed. The apparatus comprises a tube or barrel for holding a cartridge, a plate member which simulates a breech to retain the cartridge in the tube, means for simulating pressure caused by exploding gun powder, means for simulating heat caused by exploding gun powder and means for obtaining thermal data.

United States Patent 4/1964 Hagy 73/l5.6

San Miguel Sept. 2, 1975 [5 ANALOG GUN (SELECTION 0} 3,369,390 2/1968Chu et all. 73/l5.6 CONSUMABLE CARTRIDGE MATERIALS) 3,61 1,787 10/1971D'Annessa et al 73/l5.6

7 l t A h M' 5] men or g San lguel Rldgecrest Primary ExaminerDonald O.Woodiel Attorney, Agent, or FirmR. S. Sciascia; Roy Miller; [73]Assignee: The United States of America as Lloyd E. K. Pohl representedby the Secretary of the Navy, Washington, DC. ABSTRACT [22] Flled: May1974 Apparatus for testing the potential of polymeric mate- [21] App].No.: 467,172 rials for use in the manufacture of cartridges and the likeis disclosed. The apparatus comprises a tube or barrel for holding acartridge, a plate member which '3; 73/ simulates a breech to retain thecartridge in the tube, means for simulating pressure caused by exploding[58] Field of Search 73/l5.6, 167, 150 g powder, means for Simulatingheat caused y ploding gun powder and means for obtaining thermal [56]References Cited data UNITED STATES PATENTS 3J29087 4 Claims, 1 DrawingFigure ANALOG GUN (SELECTION OF CONSUMABLE CARTRIDGE MATERIALS)BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to apparatus for use in the selection ofmaterials for use in the manufacture of cartridges.

2. Description of the Prior Art.

Reasons for the desirability of cartridges fabricated from polymericmaterials are well known. Such cartridges are lighter than conventionalbrass cartridges. Such cartridges are generally less expensive thanbrass cartridges. By incorporating oxidizers into the polymericmaterial, one can make the cartridges consumable, i.e., of the typewhich will be completely or partially consumed when they are fired.Reasons for the desirability of consumable cartridges are also wellknown but need not be gone into here.

Prior art polymeric cartridges have left much to be desired insofar astheir qualities are concerned. Some do not have adequate tensilestrength to withstand the stresses and strains that they are subjectedto when they are handled and loaded. Some do not have enough heatresistance to tolerate being loaded into a gun which has been heated byrepeated firings. Some build such pressures within the gun barrel whenthey are consumed that they are unsuitable. Some consumable cartridges,in spite of the claims made for them, simply are not consumed underordinary firing conditions. Many of these and other problems could bealleviated if methods and apparatus for testing candidate polymericmaterials were improved. Insofar as is known by the inventor, the onlyprior art way by which polymeric cartridges have been tested underactual firing conditions 'BRIEFDESCRIPTION OF THE DRAWING The singleFIGURE is an exploded, perspective view of apparatus according to thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS tested.

In the drawing, the numeral 11 indicates a tubular or barrel member intowhich a cartridge or portion thereof 12 which is to be tested isinserted. In one embodiment, an end plate 13 having a threaded centerhole 14 in it is fastened to the cartridge by means of a threaded rod 15which is screwed through hole 14 and through a threaded hole (not shown)in the cartridge to draw the cartridge and end plate closely together.The threaded rod physically simulates an ignitor. In the embodimentbeing spoken of, a contoured mandrel 16 y is drawn into the cartridge 12by means of threaded rod 15 to simulate pressure produced when acartridge is fired. Naturally, in order to do this, the contouredmandrel must have a threaded hole (not shown) which rod 15 is screwedinto. To simulate heat produced by exhas been to fabricate cartridges,load them, place them SUMMARY OF THE INVENTION The present inventionresides in apparatus for obtaining relevant data on polymeric materialswhich are potentially suitable for use in the manufacture of cartridges.The apparatus is analogous to a gun in that it simulates firingconditions produced by a gun. It is advantageous over a gun in thattests relating to pressure and temperature can either be performedsimultaneously or individually. The apparatus comprises a barrel inwhich a cartridge or portion thereof to be tested is placed, an endplate to simulate a breech mechanism and hold the cartridge in place, acontoured mandrel which can be forced into the cartridge and utilized tosimulate gas pressure produced by exploding gun powder and a connectingrod to simulate the cartridges igniter. One or more thermocouplesconnected to the cartridge through holes in the end plate are utilizedto provide thermal data and exhaust gases from a gas generator are usedto simulate temperatures and heat flux produced by exploding gun powder.

ploding powder a gas generator 17 is utilized. In the drawing, the gasgenerator is depicted as a rocket but other gas generators could beutilized.

In the embodiment of the invention being discussed, pressure issimulated relatively slowly by drawing the parts (mandrel, cartridge andend plate) together slowly with rod 15. And, when the gas generator isactivated to produce gases which simulate heat which would be producedby exploding powder, a plurality of thermocouples 18 attached to thecartridge through small holes 17 in end plate 13 and to one or morerecording instruments l9 remote from the analog gun of this inventionare utilized to record temperature information. It may also be desirableto attach thermocouples 20 to the end plate itself which simulates abreech mechanism and to a recording instrument. The end plate acts as acalorimeter and data obtained by taking heat measurements from it can beuseful. The recording instrument may be an analog tape recorder whichrecords voltage data from the thermocouples. In this way, data obtainedcan be handled at liesure later by well known methods.

In a second embodiment of the invention, rod 15 may be attached, bymeans of threads to mandrel l6 and, at its other end, to a pressure jack(not shown) located behind the apparatus with the center portion of therod being smooth so that it will slide freely through the holes in thecartridge and the end plate. In this embodiment, pressure may be appliedvery quickly by activating the pressure jack and pulling the countouredmandrel into the cartridge. It should be noted that this embodiment moreclosely approximates what actually happens (insofar as pressure isconcerned) when a cartridge is actually fired than does the firstembodiment. When a cartridge is fired, pressure quickly builds up forapproximately 5 milliseconds and then subsides.

Apparatus according to this invention may be utilized in many differentways. For example, data having to do with what happens when pressurebuilds up within a cartridge may be obtained by slowly drawing mandrel16 into Cartridge 12. As another example, data having to do with whathappens insofar as pressure is concerned may be obtained by utilizing apressure jack and rod to quickly jerk mandrel 16 into cartridge 12. Asanother example, data on the effect of heat alone may be obtained bysimply firing gas generator 17 into cartridge 12 while the cartridgeisimprisoned in the tube 11 by means of end plate 13. As another example,data may be obtained by simultaneously applying pressure and heat.to'the cartridge. 7

If it is desired, a plate may be placed between the gas generator andthe end of tube 1 1 so that the gas generator can be activated and itsexhaust gases allowed to build up to any desired temperature. Then, atany selected time, the plate can be removed to allow the full force ofthe heat to suddenly hit the cartridge.

Since it will be desired to obtain heat measurements while mandrel 16 isinserted in cartridge 12, it is preferred that mandrel 16 be fabricatedfrom a material which conducts heat well. Either aluminum or copper issatisfactory and there are undoubtedly other satisfactory materials aswell. Since the end plate must act as a calorimeter, it is preferredthat it be fabricated from a good calorimetric type material such asvery pure iron. Armco iron is satisfactory. The other parts of theapparatus (tube, rod and gas generator) may, of course, befabricatedfrom steel or similar materials from which, guns and gas generators areordinarily fabricated. Those skilled in the art of obtaining thermaldata will, of course, have no difficulty in knowing what thethermocouples and related instruments are fabricated from.

; The instant invention has been described as being re- I .lated toapparatus for determining the suitability of polymeric materials for usein the manufacture of cartridges. It will be recognized that theapparatus of this invention could be used to conduct tests on polymericmaterials which are candidates for use in either consumable ornonconsumable cartridges. It will also be recognized that the apparatusof this invention could be used to conduct tests on materials, otherthan polymeric, which are candidates for use in the manufacture ofcartridges. The evaluation of rim removal designs can also be performed.

What is claimed is:

1. Apparatus for obtaining data concerning the effects of heat andpressure on a material comprising? a tube member to receive saidmaterial;

an end plate adapted to retain said material in said tube member havinga threaded center hole which permits the material to be fastened to itby means of a threaded rod and a plurality of small holes through whichtemperature measuring apparatus can be inserted and attached to thematerial;

means for applying pressure to said material;

means for applying heat to said material; and

means for measuring and recording the heat applied to said material.

2. Apparatus according to claim 1 wherein the means for applyingpressure is a contoured mandrel which is drawn into the material bymeans of a threaded rod.

3. Apparatus according to claim 2 wherein the means for applying heat isprovided by hot exhaust gases from a gas generator.

4. Apparatus according to claim 3 wherein the means for measuring andrecording heat comprises at least one thermocouple and one recordinginstrument in

1. Apparatus for obtaining data concerning the effects of heat andpressure on a material comprising: a tube member to receive saidmaterial; an end plate adapted to retain said material in said tubemember having a threaded center hole which permits the material to befastened to it by means of a threaded rod and a plurality of small holesthrough which temperature measuring apparatus can be inserted andattached to the material; means for applying pressure to said material;means for applying heat to said material; and means for measuring andrecording the heat applied to said material.
 2. Apparatus according toclaim 1 wherein the means for applying pressure is a contoured mandrelwhich is drawn into the material by means of a threaded rod. 3.Apparatus according to claim 2 wherein the means for applying heat isprovided by hot exhaust gases from a gas generator.
 4. Apparatusaccording to claim 3 wherein the means for measuring and recording heatcomprises at least one thermocouple and one recording instrument incombination.